From ece2b3041c1182b41a17937d1894c58bd0b54364 Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Fri, 26 Nov 2021 14:37:40 +0000
Subject: [PATCH] input: edt-ft5x06: Handle unreliable TOUCH_UP events

The ft5x06 is unreliable in sending touch up events, so some
touch IDs can become stuck in the detected state.

Ensure that IDs that are unreported by the controller are
released.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 drivers/input/touchscreen/edt-ft5x06.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

--- a/drivers/input/touchscreen/edt-ft5x06.c
+++ b/drivers/input/touchscreen/edt-ft5x06.c
@@ -130,6 +130,7 @@ struct edt_ft5x06_ts_data {
 	int offset_y;
 	int report_rate;
 	int max_support_points;
+	unsigned int known_ids;
 
 	char name[EDT_NAME_LEN];
 	char fw_version[EDT_NAME_LEN];
@@ -208,6 +209,9 @@ static irqreturn_t edt_ft5x06_ts_isr(int
 	int i, type, x, y, id;
 	int offset, tplen, datalen, crclen;
 	int error;
+	unsigned int active_ids = 0, known_ids = tsdata->known_ids;
+	long released_ids;
+	int b = 0;
 
 	switch (tsdata->version) {
 	case EDT_M06:
@@ -280,10 +284,25 @@ static irqreturn_t edt_ft5x06_ts_isr(int
 
 		input_mt_slot(tsdata->input, id);
 		if (input_mt_report_slot_state(tsdata->input, MT_TOOL_FINGER,
-					       type != TOUCH_EVENT_UP))
+					       type != TOUCH_EVENT_UP)) {
 			touchscreen_report_pos(tsdata->input, &tsdata->prop,
 					       x, y, true);
+			active_ids |= BIT(id);
+		} else {
+			known_ids &= ~BIT(id);
+		}
+	}
+
+	/* One issue with the device is the TOUCH_UP message is not always
+	 * returned. Instead track which ids we know about and report when they
+	 * are no longer updated
+	 */
+	released_ids = known_ids & ~active_ids;
+	for_each_set_bit_from(b, &released_ids, tsdata->max_support_points) {
+		input_mt_slot(tsdata->input, b);
+		input_mt_report_slot_inactive(tsdata->input);
 	}
+	tsdata->known_ids = active_ids;
 
 	input_mt_report_pointer_emulation(tsdata->input, true);
 	input_sync(tsdata->input);
